Hierarchical states in the Compositional Interchange Format

TL;DR

This paper introduces hierarchical states into the CIF language, enabling stepwise refinement and more succinct hybrid system models, while maintaining compatibility with existing tools through hierarchy elimination procedures.

Contribution

It extends CIF with a hierarchy mechanism (hCIF), providing a semantics that minimally redesigns atomic entity rules and allows hierarchy removal for tool reuse.

Findings

Semantic framework for hierarchy in CIF

Hierarchy can be eliminated from models

Supports top-down hybrid system development

Abstract

CIF is a language designed for two purposes, namely as a specification language for hybrid systems and as an interchange format for allowing model transformations between other languages for hybrid systems. To facilitate the top-down development of a hybrid system and also to be able to express models more succinctly in the CIF formalism, we need a mechanism for stepwise refinement. In this paper, we add the notion of hierarchy to a subset of the CIF language, which we call hCIF. The semantic domain of the CIF formalism is a hybrid transition system, constructed using structural operational semantics. The goal of this paper is to present a semantics for hierarchy in such a way that only the SOS rules for atomic entities in hCIF are redesigned in comparison to CIF. Furthermore, to be able to reuse existing tools like simulators of the CIF language, a procedure to eliminate hierarchy from an automaton is given.